FIELD OF THE INVENTION
This invention lies in the field of remote indicating devices. More particularly, it is concerned with indicating the position of a piston within a cylinder. An example of the application of the invention is its use with a remotely controlled and operated valve, the valve closure member being positioned by means of a piston in a cylinder through which a control fluid is passed.
In the prior art, there has been no way of detecting or indicating the position of the piston in such a remote controlled device except by having the piston rod itself be sealed through and project beyond the end of the cylinder. This involves additional expense and difficulty from leakage through the seals, etc.